Celtics center Aron Baynes has been diagnosed with a grade 2 ankle sprain, according to a tweet from the team. Coach Brad Stevens confirmed the injury, which Baynes suffered in tonight’s loss to the Sixers.

A grade 2 sprain often carries a recovery time of 4-6 weeks, so Baynes may not be able to return before the end of the regular season. Daniel Theis and Robert Williams will likely see increased playing time until he gets healthy.

It’s the latest in a series of bad breaks for Baynes, who recently returned to the lineup after missing more than a month with a left foot contusion. He also missed 13 games earlier in the season with a broken bone in his left hand. Baynes has been limited to 43 games and is averaging 5.3 points and 4.2 rebounds per night.